Flow diverters of the prior art, especially when used in back-to-back installations, were complex and costly to install, and some could be prone to leak unless installed with great care, especially those that required hydraulic pressure of the water to seal the valve. Adapters could also be used to obtain standard flow patterns and avoid reversal of hot and cold water controls of the control valve involved in the back-to-back installations. The use of adapters required extra parts to be carried in inventory and added to the cost of the installation.